One criterion would be at ground level (at take-off, presumably) where someone’s around to hear it
Another case might at altitude at maximum thrust–would that be louder, were it at ground level, but the rarefied atmosphere would mitigate the acoustic pressure? (That might very well be muddle headed thinking on my part to begin with.)
I’ve read that the tu-95 bear is really damn loud since its props’ tips break the sound barrier, even if the plane doesn’t. Not sure if that makes it The Loudest or even louder than a B1 though. I’ll see if I can dig up some cites…
One can’t ignore the Republic XF-84H “Thunderscreech”. Supersonic proptips even at idle, let alone full power. Caused nausea, headaches, and even one seizure.
At one Prestwick Air Show when I was a kid, three Harriers did a display. The finale was the three of them in hover close together, bowing to the crowd. I’ve heard a Concorde taking off at close range, and Vulcans going overhead at low level, but at least those were quickly getting farther away from you. The hovering Harriers turned mere sound into something intensely physical.
I’ve probably told this tale before, but I’ve been overflow by a B-1 at very low altitude - maybe 100~200 ft.
A buddy’s family owned land along a creek system and a series of flood control dams were built along it. Early one morning we were in a little boat, fishing in one of these lakes. I heard some sort of hissing behind us and turned around to see B-1 bearing down on us, and I mean * right there *. It flew nearly directly over us, but off to the side enough to see a profile view. As it passed over, the hissing turned to quite a roar, but not deafening. They were carving down the creek channel, wings extended, so weren’t at full throttle.
I hope they saw us, at that altitude I imagine they were definitely trained on the terrain ahead. And just like that, they were gone. In all my years of living around here, I’ve never seen another B-1 flying like that, quite a treat.
That’s the one I came in to mention. There were some truly fucking insane ideas in aviation back then, and this plane has got to be on the short list. Nothing was too crazy to try.
I used to make deliveries to a GM plant in OKC just across a street from Tinker AFB. Many different aircraft, if they didn’t fly out of there, certainly did “Touch and Goes” there. B-1s were certainly much louder than B-52s, E-3s and other versions of a C-135, and a KC-10. And that’s from the inside of a pretty well insulated Freightliner Century or Volvo 660.
Had a B-1 do a low, slow fly-by at an airshow once. After it had traveled the length of the runway it pitched up and away and went to afterburner. Probably the loudest thing I’ve ever heard; that’s the only plane for which I’ve really felt compelled to cover my ears. They’re relatively big engines, with afterburner, and there’s four of them. The Concorde had more thrust, but I don’t know whether they made any effort at noise suppression for that plane.
B-52 had a little more overall thrust, but no afterburner; I’d be surprised if it was louder than the B-1.
Tough call. I’d say the B-1 wins for peak sound, but the Harrier wins for longest sustained loud when hovering. I used to live near McConnell AFB in Wichita (over 20 years ago now) and saw/heard B-1s every day. At one airshow there they had 2 B-1s displaying together. One was doing a “dirty pass” with wings forward, gear down, basically going as slow as possible. The announcer was explaining all about it to keep the crowd’s attention focused on it. Meanwhile the other one had done a wide circle and came in with wings back, afterburners on and overtook it right at the midpoint of the runway before standing on its tail and going nearly straight up. That was loud and EVERYONE jumped.
I’m in the UK now and have seen the Harriers do their thing at Fairford and Farnborough a few times. When you’re close enough during the hover you really feel the sound. I’ve seen the Vulcan display a couple times too and it’s quite loud. Sadly, it seems to be permanently grounded now.
The new F-35B displayed at Farnborough for the first time this year. I live about a mile from the runway and when it went over my house it set off car alarms in my road.
Now I’m wondering how many people could still attest to how loud the XB-70 was on takeoff or low level…or if it hasn’t passed out of living memory by now.
*Take thy shield take thy sword
All thy weapons to the sky
Ye shall need them when Odin bid thee rise
For none but the brave
Shall rise up from the grave
To see the Valkyries fly!
*
I see various assertions that the max dB for the B-1 is somewhere in the range of 130 for either takeoff or a low pass with afterburners. That’s damn loud.
The engines in a B-1 are basically the same as the engines used in F-16s and F-15s. The F135 that powers the F-35 aircraft are roughly 40% more powerful than those legacy engines, meaning the F-35 is one damn loud airplane for having a single engine. Compared to an F-16, an F-35 is probably in the range of 15 dB louder, or as we would perceive it, about two-and-a-half times louder. Still not as loud as a B-1, which is maybe another two or three times louder than an F-35, but thought I’d throw that out there.
Damn, ya beat me by two minutes on this. Knew I shouldn’t have gone up for a coffee refill.
I have heard that among the XB-70’s many faults was a phenomenal noise level. As you say, there may not be anyone left to comment, but maybe one of the av buffs can find a word or two in the books and records?
The other, speaking of sound (heh, referring to me and it), was interesting for two reasons: 1) you know how as background “effects” sounds in silent tapes of planes in History Chanel of random propeller or artillery sounds? Never have they seen more fake and inappropriate in this of this little excerpt on the F-84H from a doc, with good footage on the ground and in flight: The Republic F-84H Thunderstreak - (Thunder Screech) - YouTube
Back to the acoustics: that vid said the plane produced “about 900 sonic booms per minute.”
I don’t get this. I thought the sonic boom was the shock wave catching up, and was generated in a transition from subsonic to supersonic. Those wing tips don’t dip above and below that speed, but stay there, right?
Other questions:
Sonic booms are not all one volume, right? I’ve only heard one, in Israel, from some invisible jet (Israeli, I hope) somewhere. The shock wave, like all waves, depends on the initiating mass, so an aircraft carrier hitting Mach 1 (USA!) is louder?
2a) Is the frequency envelope the same for all sonic booms?
The prize of the F-84H is won due to the propellers, yet the others, except the Bear, are engines (which in fact I thought were the only reason when I posted).
Is it the roar produced by the air traveling through the aircraft engine (subsonic, of course) and the combustion exhaust? The turbine blades are propellers also–can that sound be “separated” as an acoustic phenomenon with the same analytics as the propellers?
(Assuming you mean the propeller tips rather than the wing tips.)
If the propeller tips are travelling faster than the speed of sound, and the roots of the blades are travelling slower than the speed of sound, there must be a point somewhere along each blade that is exactly at mach 1.
